Hemorheologic alterations in hypertension: chicken or egg?

The serious pathophysiologic consequences of systemic hypertension have prompted numerous basic science and clinical studies related to cardiac or vascular abnormalities. More recently, hemorheologic alterations in hypertension have been explored in an attempt to determine the import of theologic factors vis-a-vis the elevated total peripheral resistance observed in hypertensive patients. To date, various studies have documented several abnormalities (e.g., increased blood and plasma viscosity, elevated hematocrit), with some suggesting altered RBC or WBC rigidity. However, there is much less information relevant to the "chicken or egg" problems: (1) are reported hemorheological abnormalities the cause or the result of hypertension; (2) does normalization of blood pressure also normalize hemorheological parameters? In overview, the current literature indicates that hemorheology and hypertension may be linked, but that the details of this association and its cause-effect relations remain unclear.